1. Field of the Invention
The present invention relates to operations in a wellbore. More specifically, the invention relates to a system and method for excavating a lateral wellbore from a primary wellbore.
2. Description of the Related Art
Hydrocarbon producing wellbores extend subsurface and intersect subterranean formations where hydrocarbons are trapped. The wellbores generally are created by drill bits that are on the end of a drill string, where a drive system above the opening to the wellbore rotates the drill string and bit. Cutting elements are usually provided on the drill bit that scrape the bottom of the wellbore as the bit is rotated and excavate material thereby deepening the wellbore. Drilling fluid is typically pumped down the drill string and directed from the drill bit into the wellbore. The drilling fluid flows back up the wellbore in an annulus between the drill string and walls of the wellbore. Cuttings produced while excavating are carried up the wellbore with the circulating drilling fluid. Drill strings are typically made up of tubular sections attached by engaging threads on ends of adjacent sections to form threaded connections.
In some instances the wellbore is made up of a primary or main wellbore with one or more lateral wellbores that branch from the main wellbore. Typically, lateral wellbores that branch from an existing open-hole horizontal portion of a main wellbore are initiated from a “low” side of the main wellbore because of the gravity effect and a lack of an anchor for the drill bit. This may seriously limit workover completion options for existing horizontal wellbores to control flow or optimize production of each lateral wellbore created.